The line BD cuts the rhombus in half, bisecting the angles CDA and ABC. Since these angles are (1/2)*(360 - 2*60) = 120 degrees, triangle ABD is an equilateral triangle. Thus MD = 16.

Triangle ACD is an isosceles triangle, with the two equal sides (CD and DA) of 16, and vertex angle 120 degrees, so AC will be

AC = sqrt{CD^2 + AD^2 - 2*CD*AD*cos(12)} <-- By the Law of Cosines

AC = 27.7128

Try working it from here.

-Dan